Python: Find a palindrome of a given length containing a given string

Last update on April 17 2025 13:08:59 (UTC/GMT +8 hours)

Generate Palindrome of Specific Length

Write a Python program to generate a palindrome of a given length from a string.

Input:  madam , 7
Output:
madaadam

Input:  madam , 6
Output:
maddam

Input: madam , 5
Output:
maaaam

Input:  madam , 3
Output:
maam

Input:  madam , 2
Output:
mm 

Input: madam , 1
Output:
aa

Sample Solution:

Python Code:

# License: https://bit.ly/3oLErEI

# Function to generate a palindrome of a given length from a string
def test(s, length):
    s_index = 0
    # Calculate the half length of the palindrome
    length_half = (length - (length % 2)) // 2
    ans = ""
    
    # Build the first half of the palindrome
    while len(ans) < length_half:
        ans += s[s_index % len(s)]
        s_index += 1
    
    # Add a middle character if the length is odd
    if length % 2 == 1:
        ans += "a"
    
    # Complete the palindrome by adding the reversed first half
    return ans + ans[::-1]

# Test cases with different string and palindrome lengths
s = 'madam'
length = 7
print("String and length of the palindrome:", s, ",", length)
print("Palindrome of the said string and length:")
print(test(s, length))

s = 'madam'
length = 6
print("\nString and length of the palindrome:", s, ",", length)
print("Palindrome of the said string and length:")
print(test(s, length))

length = 5
print("\nString and length of the palindrome:", s, ",", length)
print("Palindrome of the said string and length:")
print(test(s, length))

length = 3
print("\nString and length of the palindrome:", s, ",", length)
print("Palindrome of the said string and length:")
print(test(s, length))

length = 2
print("\nString and length of the palindrome:", s, ",", length)
print("Palindrome of the said string and length:")
print(test(s, length))

length = 1
print("\nString and length of the palindrome:", s, ",", length)
print("Palindrome of the said string and length:")
print(test(s, length))

Sample Output:

String and length of the palindrome: madam , 7
Palindrome of the said string and length:
madaadam

String and length of the palindrome: madam , 6
Palindrome of the said string and length:
maddam

String and length of the palindrome: madam , 5
Palindrome of the said string and length:
maaaam

String and length of the palindrome: madam , 3
Palindrome of the said string and length:
maam

String and length of the palindrome: madam , 2
Palindrome of the said string and length:
mm

String and length of the palindrome: madam , 1
Palindrome of the said string and length:
aa

Flowchart:

For more Practice: Solve these Related Problems:

Write a Python program to generate a palindrome of a specified length from a given base string by mirroring its halves.
Write a Python program to construct a palindrome by expanding or truncating an input string to meet the target length.
Write a Python program to produce a palindrome of specific length by repeating and reflecting parts of the input string.
Write a Python program to implement palindrome generation using slicing to mirror the string until the desired length is reached.

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Python Code Editor :

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